Dunstan says he is owed about $450,000 for periods between 1991 and 2008, the same year he was released from prison.

In 2000 he was found guilty in the ACT Supreme Court on multiple charges of posting an explosive and attempting to inflict grievous bodily harm.

Two years earlier he mailed bombs to 28 people who he believed had wronged him. One exploded at the Fyshwick mail centre, injuring a postal worker.

Dunstan was jailed for nine years.

But for more than 20 years he has fought Comcare over compensation he sought for depression and harassment following a soured workplace relationship.

Both he and his former lover, known as Ms X, lodged workplace complaints against each other.

In August the tribunal found Dunstan had suffered chronic depression and his employment had materially contributed.

''It was a contributing factor … because it provided the opportunity for Ms X's presence at his place of work. That enabled her to be a presence in his life,'' it said.

The tribunal said Ms X was then in a position where she could be demanding, belligerent and sexually provocative towards Dunstan.

The tribunal tasked Comcare to start working out how much Dunstan was owed.

According to Dunstan's letter, obtained by The Canberra Times, Comcare contacted him in September and said it had decided not to appeal against the decision.

The letter states Dunstan received an interim payment, which he slammed as ''an arbitrary small fraction'' of what he was owed.

''Continuing uncertainty over the amount and timing of receipt of my entitlements and the accumulating unrecoverable economic detriment that I am incurring aggravates my chronic depressive illness,'' he wrote.